1. Technical Field
The present invention relates to a direct-type backlight unit including a plurality of light sources, and an electro-optical device and an electronic apparatus using the backlight unit.
2. Related Art
In the related art, in general, a liquid crystal display (LCD), which is an electro-optical device, includes a display panel that displays an image and a backlight unit that is provided on the rear side of the display panel and emits light to the display panel.
A direct-type backlight unit has been proposed which includes a plurality of light sources arranged immediately below the display panel (for example, JP-A-2006-244990 and JP-A-2007-128129).
The direct-type backlight unit disclosed in JP-A-2006-244990 and JP-A-2007-128129 includes a box-shaped case with a lower plate, a plurality of light sources that are provided in the case, and a display panel that is arranged so as to cover an opening of the case. The case includes a lower plate on which a plurality of light sources are arranged in a line and a plurality of side walls that are obliquely provided at the edge of the lower plate. The plurality of side walls are provided at the same inclination angle.
Light emitted from the plurality of light sources and light reflected from the inner surfaces (reflecting surfaces) of the plurality of side walls irradiate toward a radiation area surrounded by the upper ends of the plurality of side walls.
However, in JP-A-2006-244990 and JP-A-2007-128129, during the assembly of the backlight unit, when a plurality of light sources are arranged in a line, it is difficult to accurately arrange the light sources on the lower plate of the case such that the light sources are equidistant from the side walls. As a result, a variation in the arrangement positions of the light sources occurs.
Therefore, when the distance between the light source and the side wall is large, the amount of light reflected from the reflecting surface of the side wall is reduced. When the distance between the light source and the side wall is small, the amount of light reflected from the reflecting surface of the side wall is increased. As a result, the amount of light in the radiation area becomes non-uniform. In addition, when the distance between the side wall and the light source is large, the amount of light reflected from the reflecting surface of the side wall is reduced. As a result, the amount of light emitted to the edge of the radiation area is reduced, and optical characteristics deteriorate.
In a liquid crystal display device, which is an assembly of the backlight unit and the display panel, when the amount of light in the radiation area of the backlight unit becomes non-uniform, display irregularities, such as brightness irregularity and color irregularity, are likely to occur in an effective display area of the display panel in which an image is displayed.